The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag on the side of the occupant when the impact is applied to the vehicle from the side of the vehicle seat.
A side airbag apparatus having an airbag and an inflator is effective as an apparatus that protects an occupant seated in an automobile seat when an impact is applied to the seat from a side, for example, due to a side collision. The outer shape of the airbag is formed by an airbag body. The inflator is arranged at the rear end of the airbag body and fixed to the automobile.
In the above described side airbag apparatus, when an impact is applied from the side to a body side portion of the automobile, for example, to a side door, the inflator supplies inflation gas to the airbag body. The airbag body is deployed and inflated between the upper body of the occupant and the body side portion, which bulges into the interior of the automobile. The upper body of the occupant is restrained by the airbag body, and the impact from the side, which is transmitted to the upper body through the body side portion, is alleviated, so that the upper body is protected from the impact.
As one form of the above described side airbag apparatus, for example, Japanese National Phase Laid-Open Patent Publication No. 2007-510581 discloses a side airbag apparatus that includes an inflated-dimension limiter (tether) bridging opposite inner surfaces of the airbag body. The inflated-dimension limiter is shaped as a sheet that extends in the front-rear direction and has a constant width in the up-down direction. The inflated-dimension limiter is joined to the front end of the airbag body by a front joint portion provided at the front end and is joined to the rear end of the airbag body by a rear joint portion provided at the rear end.
When the airbag body is inflated, the inflated-dimension limiter (tether) is tensioned in the front-rear direction. The tensioned inflated-dimension limiter limits the inflated dimension of the airbag body in the front-rear direction, so that the airbag body acts to inflate in the automobile width direction. In the section of the airbag body where the inflated-dimension limiter is provided, the inflated dimension in the front-rear direction is small compared to the case in which the inflated-dimension limiter is not provided, and the inflated dimension in the automobile width direction is increased. This improves the performance of restraining the occupant.
In the side airbag apparatus disclosed in the above-mentioned publication, the up-down dimension of the front joint portion and the up-down dimension of the rear joint portion are the same. The inflated dimension in the automobile width direction of the airbag body increases mostly in the section between the rear joint portion and the front joint portion. Therefore, there is room for improvement in reducing the inflated dimension in the front-rear direction of the airbag body and increasing the inflated dimension in the automobile width direction, thereby improving the performance of restraining the occupant. This is not limited to side airbag apparatuses for automobiles but applies to any side airbag apparatuses for other types of vehicles.